Suspended ceiling integrated air distribution system

ABSTRACT

A plurality of air distribution subassemblies, each having spaced sidewalls defining an air distribution passage therebetween, are mounted in a linear array transversely of a plurality of preexisting suspended ceiling main runner members, in one embodiment straddling cross T-bar members spanning the distance between said main runners, wherein a continuous air supply plenum is mounted on two or more adjacent subassemblies of such air distribution subassemblies with a continuous air supply outlet therein along a lower portion thereof and extending across the associated main runner, and in one said embodiment across the intersection of a main runner and across T-bar, to provide an effectively continuous linear air distribution passage through said ceiling across the main support members of the preexisting ceiling grid or support system.

United States Patent [72] Inventor Robert R. Lambert 442 W. LeadoraAve., Glendnra, Calif. 91740 [21] Appl. No. 815,835 [22] Filed Apr. 14,1969 [45] Patented May 11, 1971 [54] SUSPENDED CEILING INTEGRATED AIRDISTRIBUTION SYSTEM 6 Claims, 9 Drawing Figs.

[52] US. Cl 98/40, 52/303 [51] Int. Cl F24f 13/06 [50] Field of Search98/400, 40, 400 (L); 52/665, 303, 201, 204

[5 6] References Cited UNITED STATES PATENTS 3,187,661 6/1965 Dail .698/40 ABSTRACT: A plurality of air distribution subassemblies,

each having spaced sidewalls defining an air distribution passagetherebetween, are mounted in a linear array transversely of a pluralityof preexisting suspended ceiling main runner members, in one embodimentstraddling cross T-bar members spanning the distance between said mainrunners, wherein a continuous air supply plenum is mounted on two ormore adjacent subassemblies of such air distribution subassemblies witha continuous air supply outlet therein along a lower portion thereof andextending across the associated main runner, and in one said embodimentacross the intersection of a main runner and across T-bar, to provide aneffectively continuous linear air distribution passage through saidceiling across the main support members of the preexisting ceiling gridor support system.

Pate nted May 11, 1971 4 Sheets-Sheet 1' J INVENTO/Q RoaserB. 10/1155873 ma, a ,Mz

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Patented May 11, 1971 4 Sheets-Sheet 4 l'zvvewro e. 206527 R 2 145.52 r.7 $7M, a; a fad firr e/vsus.

SUSPENDED CEILING INTEGRATED AIR DISTRIBUTION SYSTEM BACKGROUND OF THEINVENTION Many suspended ceiling installations have been made in thepast wherein a grid of main and cross inverted T-bars are used forsupporting acoustical tile suspended from a ceiling or soffitthereabove. Various air distribution systems have been devisedheretofore which can be incorporated in such suspended ceiling systemsas a part of the original design thereof and in some instances, as anadded, later installed system. The invention of the present applicationis directed to ceiling integrated air distribution systems of the latertype wherein an air distribution system is to be installed in apreexisting suspended ceiling grid.

Heretofore, continuous linear air distribution through a ceiling hasbeen effected only by means of an originally incorporated continuous air'bar member which is installed originally as part of the ceilingstructure for suspending the ceiling tile. In adding air distributionsystems to preexisting ceiling grids where main and cross T-bars havealready been installed, the air distribution systems have taken the formof plug-in individual units which may be located in various portions ofthe ceiling. None of these latter added air distribution systems haveprovided an effectively continuous linear air distribution system alonga ceiling which operates and functions in the manner of theaforementioned originally installed linear air distribution means.

By way of example, in my prior US. Pat. No. 3,406,623 l disclose aplenum air diffuser assembly adapted to be seated upon the preexistinginverted T-bar support members for the ceiling, and in an alternativeembodiment therein, to straddle certain of the preexisting invertedT-bars. These units were individually supplied with conditioned airthrough the use of flex ducts to their individual plenums. Aneffectively continuous air supply across the suspended ceiling mainrunners, and particularly the intersection of the main runners and thecross T- bars, was not accomplished.

OBJECTIVES AND INVENTION SUMMARY It is therefore the primary objectiveof the present invention to disclose and provide a suspended ceilingintegrated air distribution assembly which can be easily assembled intoa preexisting suspended ceiling grid of inverted T-bars and therebyprovide an effectively continuous linear air distribution means alongthe ceiling even though the ceiling has been originally installed as anoncontinuous, interrupted grid of crossed ceiling support members.

It is a further object of the present invention to disclose a ceilingintegrated air distribution assembly as in the foregoing object whereina plurality of air distribution subassemblies may be installed betweenthe suspended ceiling main runners with a single continuous air supplyduct mounted thereto for supplyingair to adjacent subassemblies across aceiling main runner positioned between said adjacent subassemblies.

It is a still further object of the present invention to disclose andprovide a suspended ceiling integrated air distribution assembly as inthe foregoing objects wherein the plurality of subassemblies may bepositioned on the spaced ceiling main runners and straddling the ceilingcross T-bar members to provide an effectively continuous linear airdistribution means along the crossbars and across theintersection-between said crossbars and main runners.

It is another object of the present invention to disclose and provide aceiling integrated air distribution assembly as in the foregoing objectswherein certain individual subassemblies of the linear array thereof maybe utilized for return air into the ceiling plenum of the suspendedceiling while other adjacent subassemblies are utilized for air supplyacross the intersection with main runners and main and cross runners ashereinbeforc stated.

Generally stated, the foregoing objects are obtained'by the ceilingintegrated air distribution assembly in accordance with the presentinvention through the provision of a plurality of air distributionsubassemblies, each having spaced sidewalls defining an air distributionpassage therebetween and the subassemblies being mounted in a continuouslinear array transversely of and extending between the main T-barmembers of a preexisting ceiling system. In the preferred exemplaryembodiment of the present invention, such subassemblies are mounted onthe main T-bars straddling cross T-bar members, which then become partof the air distribution subassembly, while in the alternative exemplaryembodiment such subassemblies are independently supported between saidmain runners.

Further, a continuous air supply plenum, supplied by a single source ofconditioned air, is mounted on and supported by a plurality of adjacentlinearly disposed air distribution subassemblies with the plenum havinga continuous air supply outlet along alower portion thereof whichextends across at least one intersection of a main T-bar and adjacentsubassemblies. In the preferred embodiment, such intersection is alsothe intersection between the main T-bar and the cross T-bars which thesubassemblies straddle.

A more complete understanding of the suspended ceiling integrated airdistribution assembly, in accordance with the present invention, will beattained by those skilled in the art, and various other objects andadvantages of the present invention will be made known, from aconsideration of the following detailed explanation of two exemplaryembodiments thereof. Reference will be made to the appended sheets ofdrawings in which:

IN THE DRAWINGS FIG. 1 is a perspective view of an exemplary suspendedceiling support structure or grid of inverted I-bar members with which apreferred exemplary embodiment of the suspended ceiling integrated airdistribution system according to the present invention is illustrated inexploded relationship;

FIG. 2 is a cross section view of the airdistribution system of FIG. 1.integrated into the suspended ceiling of FIG. 1;

FIG. 3 is a longitudinal, detail sectional view taken in the planeIll-III of FIG. 2;

FIG. 4 is an exploded perspective view of an end of one of the diffuserassembly components of the assembly of FIGS. I through 3 shown prior toits integration into the ceiling support structure;

FIG. 5 is a detail view, in perspective, of a portion of the airdistribution system of FIGS. I through 4 at an intersection of theinverted T-bars of the ceiling grid or support system;

FIG. 6 is a perspective view of an alternative exemplary embodiment ofthe suspended ceiling integrated air distribution system according tothe present invention;

FIG. 7 is a cross-sectional view of the air distribution system of FIG.6 taken therein along the plane VII-VII;

FIG. 8 is another cross-sectional view of the system of FIG. 6 takentherein along the plane VIII-VIII; and

FIG. 9 is an exploded detail view, in perspective, of a portion of thediffuser assembly of the alternative exemplary embodiment of FIGS. 6through 8.

Referring first to the preferred exemplary embodiment of FIGS. 1 through5, it can be seen that the air distribution system in accordance withthe present invention may be integrated into a preexisting suspendedceiling system or grid of crossed inverted T-members to provide acontinuous, linear air distribution means in the ceiling which iseffectively uninterrupted by the intersections of the grid T-bars.

A typical suspended ceiling insulation employs main inverted T-runners,indicated generally at II), which are suspended from the above soffit orceiling by conventional hanger wires ll. Cross inverted T-bars l2 spanthe distance between main runners l0, and are secured thereto inconventional manner, to complete the grid system which normally supportsacoustical or other ceiling tiles 5.

As particularly contemplated within the present invention, a pluralityof diffuser units, or air distribution subassemblies, indicatedgenerally at 14, are mounted in a linear array transversely of andsupported on the main T-bar members and straddling the cross T-barmembers 12. In the foreground of FIG. 1, the subassemblies indicatedgenerally at 14 are shown positioned above the grid prior to theirassembly thereto, while the same type of assemblies 14 are shownassembled to the grid system in the background of FIG. 1. As seen inFIG. 2, when the air diffuser assemblies 14 are positioned with theiropposite ends resting on the flanges of main runners 10, they straddlethe centrally disposed cross T-bars 12 which form a part of the airdiffuser means as hereinafter described.

Again referring to FIG. 2, each diffuser assembly 14 is an assembly ofspaced sidewall members 16 and 16', the latter having upper flanges 17,17', outwardly extending midflanges 18, 18 and lower tile supportingflanges 19, 19', respectively. The upper flanges 17, 17' cooperate withthe air supply duct, as subsequently described, while the midflanges 18,18' and upstanding rails 20, 20 cooperate in mounting the assemblies 14to the main runners 10 as seen in FIG. 5.

Referring to FIG. 5, it can be seen that the ends of the airdistribution subassemblies 14 are mounted to the main runners 10 bybrackets 23, one leg of bracket 23 being received between midflange 18and rail 20 while the other leg rests on main runner 10 and is heldthereto by spring clip 24. The lower flanges, as flange 19, of the airdistribution subassemblies 14 are maintained in the same plane as thebottom flange, as flange 21, of the main runners 10.

Referring to FIG. 4, it can be seen that the ends of the airdistribution subassemblies 14 are slotted at 15 to straddle the verticalleg or web 12 of the cross T's 12. Also, as shown, the cross T's 12 maybe secured by means of clips 12 to the main inverted T-bars 10.

Each air distribution subassembly is provided with an airstraighteningcore or louvred plate 25, as seen in FIGS. 2, 3 and 4 with a pluralityof depending veins 26. Plate 25 is held between sidewalls 16 and 16 bythe closely spaced walls or ribs 27, 27 as seen in FIG. 2. Afterassembly of an air duct over the plurality of air distributionsubassemblies, as hereinafter explained, air moving horizontally abovethe diffusing units is extracted by plate 25, straightened by the veins26 and passed downwardly between walls 16, 16' of the subassemblies inknown manner. As best seen in FIG. 2, weir means in the form ofexemplary nested U-shaped channel weir members 30, and 31, 31', as morefully disclosed in US. Pat. No. 3,41 1,425, are provided in thesubassemblies between walls l6, 16 with the ends of the weir membersslidably mounted in channel like recesses 28 formed in the end plates29, as best seen in FIGS. 3 and 4. End'plates 29 are held betweensidewalls 16 and 16 by means of conventional fastening means, as metalscrews 29', secured through the sidewalls to intumed ears or flanges, asears 29", which are integral with end plates 29. The nested weir membersor channel members 30, 31 and 30, 31' may be adjusted relative to oneanother to control the direction and amount of air distributed throughthe assemblies. In the position shown in FIG. 2, the air distributionfrom the openings in plate 25 is directed by the weir members againstthe lower flange of the centrally straddled cross inverted T-bar member12 and thus outwardly generally adjacent the underside of the suspendedceiling surface in somewhat the manner disclosed and described withregard to the embodiments of air diffuser assembly of the second sheetof drawings of my prior US. Pat. No. 3,406,623. In the last-namedpatent, the inverted T-member is used as part of the air distributionassembly, as in the present case. However, the assembly or system of myprior U.S. Pat. No. 3,406,623 does not achieve the continuous linear airdistribution system of the present invention.

As further contemplated within the present invention, a singlecontinuous air supply plenum is mounted upon two or more adjacent airdistribution subassemblies 14 as shown in FIGS. 1, 2 and 3. In theexemplary embodiment, such continuous air supply plenum includes theplenum chamber assembly,

indicated generally at 50, comprised of individual sections 51 which maybe taped together into an effectively continuous duct by air sealing thejoints therebetween. In the exemplary embodiment, tape 52 has beenapplied to a joint, indicated in dotted line at 53 to seal the ducts andmake it effectively continuous. A particular run of duct may have closedends, as shown at 54 in FIG. 1. A top inlet 55 may be provided with acover plate 56 adapted to be seated thereon and providing an upwardlyextending collar 57 to removably receive flex duct, as shown in dottedline at 58. The sidewalls 59, 59' of each duct unit are adapted at theirlower ends to be mounted upon the linear array of air diffusersubassemblies as hereinafter explained.

As best seen in FIG. 2, the lower ends of the sidewalls 59, 59' of eachduct section 51 have a reduced cross section to fit within resilientmounting channel-shaped clips 60 and 60. Each resilient channel clip 60,60 is provided with a reentrantly folded footing portion, 61 and 61',respectively, and associated depending resilient finger portions 62 and62', respectively, to facilitate a snap fit mounting of the continuousduct on the plurality of linearly arranged air diffuser subassemblies14. As seen in FIG. 3, the mounting of a single continuous linear airsupply duct over a plurality of diffuser subassemblies mounted andintegrated into the preexisting ceiling system provides a continuouslinear air distribution means in the ceiling which is effectivelycontinuous across the intersection of a main inverted T-bar l0 and theauxiliary or cross inverted T-bars 12.

As will be explained in detail with regard to the following explanationof an alternative exemplary embodiment, any particular air diffusersubassembly 14, or part thereof, can be blanked off by spreading theweir means 14 to control the location of air distribution from theassemblies. Further, the ducting, or the connection between the ductingand the diffuser assemblies may be interrupted in order to allow thereturn of air through the assemblies 14 into the ceiling plenum.

Referring now to FIGS. 6 through 9, an alternative form of the exemplaryembodiment of the suspended ceiling integrated air diffuser assembly inaccordance with the present invention will be described.

In the exemplary embodiment of FIGS. 6 through 9, the alternative formof diffuser subassemblies 114 are suspended by means of hanger wires111, as best seen in FIG. 6, to provide a linear continuous arraythereof crossing spaced independently hung main ceiling support runners110. In this embodiment, the air diffuser subassemblies do not straddlecross T-bars, as in the former assembly, but are complete air diffuserswhich can control the distribution of air through a ceiling in acontinuous linear fashion crossing spaced main T-bars.

Referring to FIG. 7, the alternative exemplary embodiment of airdistribution subassemblies 114 include a pair of spaced inverted T-barmembers 116 and 116'. Members 116, 116 are provided with topflanges-117, 117' midflanges 118, 118' and upstanding ribs 120 and 120'as in the prior embodiment to facilitate mounting of the air supply ductand the mounting of the assemblies in interlocked relation to the mainbars, respectively. However, in the alternative embodiment ofsubassembly, the lower tile-supporting flanges 119 and 119' extendinwardly of the subassembly, at 121 and 121 respectively, to facilitatethe directional control of air supply through the subassemblies ashereinafter explained.

Still referring to FIG. 7, it can be seen that a pair of nested weirmeans and 131 are provided with their respective ends slidably mountedin end plate channels, as channel 128 in plate 129 in FIG. 9. As seen inFIG. 9, the end plates 129, as in the case of the prior embodiment, haveinwardly directed ears, as ear 129 which may be fastened to thesubassembly sidewalls 116 and 116' by conventional fastening means, as

for example metal screws.

An extractor plate may also be provided on the top of the subassemblies114 which also functions in mounting the air supply ducts thereon andthe suspension of the assemblies via hanger wires 1 1 l.

Referring now to FIGS. 6 and 7, extractor plate means are provided inthe form of inverted resilient channel members 125 having upwardlyinclined extractor veins 126 positioned in the bottom outlet 151 of duct150. In this embodiment, duct 150 may include a plurality of sections152 which are joined by tape 153 and are provided with end closures 154.A single air supply duct 155 may be connected by suitable means, as

collared plate 156 to one of the duct sections for supplying aircontinuously to the plurality of subassemblies 114.

As seen in FIG. 7, the resilient inverted extractor plate channel 125has depending flanges 156 and 157 adapted to fit between the spacedsidewalls and may be held thereon by the provision of spring clips 158and, 158'. The duct sections 152 may be secured'upon the upper surfaceof the inverted extractor channels 125 by provision of gasket means 159and suitable adhesive between the channel 125, gasket 159 and ductsections 152.

Referring to FIG. 8, it can be seen that in the exemplary embodiment ofFIG. 6, the centrally disposed air diffuser subassembly 114 is shownutilized as an air return for exhaust air from the air-conditioned roominto the air return plenum above the ceiling. As shown in FIGS. 6 and 8,a plurality of spaced inverted channel-shaped spring clips 170 and 171may .be mounted upon the subassembly, by means of side spring clips 172and 173. The portion of the air supply duct 150 positioned over the airdistribution subassembly 114' is preferably provided without any airdistribution outlets so that it merely serves as a conduit in conveyingair from the supply duct 155 to the outlying subassemblies. This portionmay then be used for air return into the ceiling plenum in the spacesbetween the closed ducts and subassembly 114' as seen in F IG. 8.

From the foregoing detailed description of the alternative exemplaryembodiment of FIGS. 6 through 10, it can be seen that a continuouslinear air distribution system can be installed in a preexistingsuspended ceiling system, in accordance with the present invention,without modifying the suspended ceiling grid support system, but yetstill providing an effectively continuous linear air distribution systemover extended lengths of ceiling surface. For example, the embodiment ofFIGS. 6 through 10 could be extended for the entire ceiling length orwidth of a room with various portions of the effectively continuouslinear air distribution subassemblies activated as air supply, airreturn or as closure members for a variety of air distribution functionsin a linear path. The latter embodiment may then serve as crossbarsupport means for ceiling tile supported on the main runners 110 and thetile flanges 119, 119'. In this embodiment, the subassemblies arecomplete air distribution devices in themselves and do not require theuse of the central air distribution T-member as in the first preferredexemplary embodiment.

From the foregoing detailed description of two alternative exemplaryembodiments of a suspended ceiling integrated air distribution system,in accordance with the present invention, it can be seen that aneffectively continuous linear air distribution system may be integratedinto preexisting suspended ceiling systems in'accordance with thepresent invention. The air distribution subassemblies may beindependently suspended adjacent ceiling support main runners to providesuch linear continuous air distribution across the ceiling main runnersupports or, as in the first embodiment, may be mounted upon the ceilingsupport main runners and, preferably, straddling the cross T-bar membersto provide a truly integrated air distribution system in a preexistingsuspended ceiling structure.

lclaim:

1. An interrupted, yet effectively continuous, air distribution assemblyto be integrated into a preexisting suspended ceiling tile supportinggrid of intersecting main and cross inverted T-bars, said assemblycomprising:

a plurality of air diffuser subassemblies having spaced sidewalls andend walls defining an air distribution passage therebetween, each ofsaid subassemblies extendsubassemblies form a linear array thereofextending transversely of pairs of spaced inverted T-bars each of whichintersects and thereby interrupts the linear air distribution passageformed by said array of subassemblies; and

a continuous air supply plenum associated in air supply relation withtwo or more adjacent diffuser subassemblies of said plurality and havinga continuous air supply outlet along a lower portion thereof extendingabove and across at least one or more of said T-bars intersecting saidair distribution passage to provide an effectively continuous airdistribution through said interrupted passage.

2. The interrupted, yet effectively continuous, air distributionassembly of claim 6 wherein:

said air supply plenum is mounted in air supply communication with atleast three of four adjacent subassemblies of said plurality of airdistribution assemblies, said fourth subassembly having its airdistribution passage communicating between a first space outside saidair supply plenum and above said ceiling system and a second space belowsaid ceiling system into which air is supplied from said air supplyplenum.

3. An air distribution assembly which is easily integrated into apreexisting suspended ceiling system having a grid of main and crossinverted T-bar members to provide a continuous linear air distributionmeans through said ceiling, said air distribution assembly comprising:

a plurality of air distribution subassemblies, each having spacedsidewalls defining an air distribution passage therebetween, saidsubassemblies being mounted in a linear array transversely of andsupported on said main T- bar members and straddling said cross T-barsmembers; and

a continuous air supply plenum mounted upon two or more adjacent airdistribution subassemblies of said plurality of subassemblies, saidplenum having a continuous air supply outlet along a lower portionthereof extending across at least one intersection of a main T-bar,supporting two adjacent subassemblies, and the adjacent cross T- barsand in air supply communication with each air distribution passage ofsaid last-named two subassemblies to provide effectively continuous airdistribution through said ceiling across said intersection in saidpreexisting ceiling system.

4. The air distribution assembly of claim 3 wherein:

said air supply plenum is mounted in air supply communication with atleast three of four adjacent subassemblies of said plurality of airdistribution subassemblies, said fourth subassembly having itsairdistribution passage communicating between a first space outside saidplenum above said ceiling system and a second space below said ceilingsystem into which air is supplied from said plenum.

5. The air distribution assembly of claim 3 wherein:

the opposite ends of each of said air distribution subassemblies areslotted to straddle the vertical leg of the associated inverted crossT-bar, a bottom horizontal flange of each of said crossT-bars lying inthe outlet path of the air distribution passage of the associatedsubassembly.

6. An interrupted, yet effectively continuous, air distribution assemblyto be integrated into a preexisting suspended ceiling tile-supportinggrid of intersecting main and cross inverted T-bars, said assemblycomprising:

a plurality of air diffuser subassemblies having spaced sidewalls and atleast partially open end walls to receive an upstanding leg of aninverted T-bar therethrough, said diffuser subassemblies beingpositioned in a linear array along and straddling one or more T-bars andbeing mounted at their respective ends on associated T-bars intersectedby said one or more T-bars to provide air distribution passages betweensaid spaced walls and divided by said one or more T-bars, saiddistribution passages extending along said array and being interruptedby said associated T-bars on which said subassemblies are mounted", and

3 7 7 9 O4 5 7 8 a continuous air supply plenum associated in air supplyrela- 1 continuous air supply outlet along a lower portion thereof tionwith two or more adjacent difiuser subassemblies of extending above saidone or more T-bars and across at said plurality of air diffusersubassemblies and having a least one or more of said associated T-bars.

UNIT D STATE S PATE'N' OFFICE EBT F Q TE .QFMQQRRECTION;

Patent No. 3,572,204 a Dated M 11. 121i Inventpr Robert R. Lambert It iscertified that error appears in the aboveidentified patent and that saidLetters Patent is hereby corrected as shown below:

Claifn 2, line 2, delete "6", and insert --l-- Signed and sealed this124th day of December 1971.

(SEAL) Attest: A I

EDWARD M.FLETCHER,JR. ROBERT GO'I'TSCHAUC Attesting Officer ActingCommissioner of Patents

1. An interrupted, yet effectively continuous, air distribution assemblyto be integrated into a preexisting suspended ceiling tile supportinggrid of intersecting main and cross inverted Tbars, said assemblycomprising: a plurality of air diffuser subassemblies having spacedsidewalls and end walls defining an air distribution passagetherebetween, each of said subassemblies extending between and beingsupported only at their opposite ends by a pair of spaced generallyparallel inverted T-bars of said preexisting ceiling grid, whereby saidplurality of subassemblies form a linear array thereof extendingtransversely of pairs of spaced inverted T-bars each of which intersectsand thereby interrupts the linear air distribution passage formed bysaid array of subassemblies; and a continuous air supply plenumassociated in air supply relation with two or more adjacent diffusersubassemblies of said plurality and having a continuous air supplyoutlet along a lower portion thereof extending above and across at leastone or more of said T-bars intersecting said air distribution passage toprovide an effectively continuous air distribution through saidinterrupted passage.
 2. The interrupted, yet effectively continuous, airdistribution assembly of claim 6 wherein: said air supply plenum ismounted in air supply communication with at least three of four adjacentsubassemblies of said plurality of air distribution assemblies, saidfourth subassembly having its air distribution passage communicatingbetween a first space outside said air supply plenum and above saidceiling system and a second space below said ceiling system into whichair is supplied from said air supply plenum.
 3. An air distributionassembly which is easily integrated into a preexisting suspended ceilingsystem having a grid of main and cross inverted T-bar members to providea continuous linear air distribution means through said ceiling, saidair distribution assembly comprising: a plurality of air distributionsubassemblieS, each having spaced sidewalls defining an air distributionpassage therebetween, said subassemblies being mounted in a linear arraytransversely of and supported on said main T-bar members and straddlingsaid cross T-bars members; and a continuous air supply plenum mountedupon two or more adjacent air distribution subassemblies of saidplurality of subassemblies, said plenum having a continuous air supplyoutlet along a lower portion thereof extending across at least oneintersection of a main T-bar, supporting two adjacent subassemblies, andthe adjacent cross T-bars and in air supply communication with each airdistribution passage of said last-named two subassemblies to provideeffectively continuous air distribution through said ceiling across saidintersection in said preexisting ceiling system.
 4. The air distributionassembly of claim 3 wherein: said air supply plenum is mounted in airsupply communication with at least three of four adjacent subassembliesof said plurality of air distribution subassemblies, said fourthsubassembly having its air distribution passage communicating between afirst space outside said plenum above said ceiling system and a secondspace below said ceiling system into which air is supplied from saidplenum.
 5. The air distribution assembly of claim 3 wherein: theopposite ends of each of said air distribution subassemblies are slottedto straddle the vertical leg of the associated inverted cross T-bar, abottom horizontal flange of each of said cross T-bars lying in theoutlet path of the air distribution passage of the associatedsubassembly.
 6. An interrupted, yet effectively continuous, airdistribution assembly to be integrated into a preexisting suspendedceiling tile-supporting grid of intersecting main and cross invertedT-bars, said assembly comprising: a plurality of air diffusersubassemblies having spaced sidewalls and at least partially open endwalls to receive an upstanding leg of an inverted T-bar therethrough,said diffuser subassemblies being positioned in a linear array along andstraddling one or more T-bars and being mounted at their respective endson associated T-bars intersected by said one or more T-bars to provideair distribution passages between said spaced walls and divided by saidone or more T-bars, said distribution passages extending along saidarray and being interrupted by said associated T-bars on which saidsubassemblies are mounted; and a continuous air supply plenum associatedin air supply relation with two or more adjacent diffuser subassembliesof said plurality of air diffuser subassemblies and having a continuousair supply outlet along a lower portion thereof extending above said oneor more T-bars and across at least one or more of said associatedT-bars.